A system is conventionally known which uses level information stored in an SD card to restrict the use of a shared personal computer (refer to Patent Document 1). The system stores, in the SD card, authentication information for permission for the use of the personal computer, policy information for restricting the operations of a user, and authorization level information indicating the authorization level of the user, permits the use of the personal computer by the personal computer checking the authentication information of the SD card against authentication information stored in the personal computer, and authenticating the authentication in restricts the personal computer to functions corresponding to the authorization level information and policy information stored in the SD card, and allows a user possessing the SD card to use the personal computer.